I have a public/private key pair. Neither of them have any sort of passphrase associated with them.

Whenever I try to ssh using either the private or public(and I'm pretty sure I should only be using the public key), I get queried for a passphrase, and then of course can't connect up.

Anyone have any idea how to get around this? Am I typing some command incorretly? I am trying to ssh into a server that I have setup in my ~/.ssh/config file(correctly, since this exact same setup works on another server) with the key stored in ~/.ec2/key.ppk

I've also tried using puttygen.exe to generate a new private key WITH a passphrase, and then using that key, and when I type the passphrase, it still fails.

Correct, this is a key generated by puttygen from a key that works in putty. When I putty into the same server(from the machine that hosts the cygwin instance) it works fine with the exact same key. When i try to connect via ssh from cygwin, it bombs out. I'm confused how to make this work.
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llaskinJun 25 '10 at 13:38

I think mrverrall's points is that the file format for the PuTTY private key is not the same as the file format used for OpenSSH (the ssh client in cygwin). So OpenSSH is just failing to use the private key data because it can't figure out what the data means. But PuTTY has an "export" option, so you can get data in the "PEM" format needed.
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Phil PJan 23 '11 at 21:44

When you set up your public key, you probably (perhaps inadvertently) set it up with a passphrase.

You probably need to start fresh -- I haven't used puttygen, but you can delete (or rename) the public key in your .ssh directory, use ssh-keygen to generate a new one (being sure not to provide a passphrase), and then share the public_key out to the authorized_keys file on the server you're trying to connect to.

You may need to also remove your old passphrase-key from the authorized-keys file on the server you're connecting to.

One thing to check, if your sshd_config file has StrictModes=yes , then the $HOME directory or $HOME/.ssh directory must not be world writable to group or other. Otherwise authentication fails no matter what.